#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

char *mp3path = "test.mp3";

static const unsigned int CRC32_Table2[256] =
{
	0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9, 0x130476DC, 0x17C56B6B, 0x1A864DB2, 0x1E475005,
	0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61, 0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD,
	0x4C11DB70, 0x48D0C6C7, 0x4593E01E, 0x4152FDA9, 0x5F15ADAC, 0x5BD4B01B, 0x569796C2, 0x52568B75,
	0x6A1936C8, 0x6ED82B7F, 0x639B0DA6, 0x675A1011, 0x791D4014, 0x7DDC5DA3, 0x709F7B7A, 0x745E66CD,
	0x9823B6E0, 0x9CE2AB57, 0x91A18D8E, 0x95609039, 0x8B27C03C, 0x8FE6DD8B, 0x82A5FB52, 0x8664E6E5,
	0xBE2B5B58, 0xBAEA46EF, 0xB7A96036, 0xB3687D81, 0xAD2F2D84, 0xA9EE3033, 0xA4AD16EA, 0xA06C0B5D,
	0xD4326D90, 0xD0F37027, 0xDDB056FE, 0xD9714B49, 0xC7361B4C, 0xC3F706FB, 0xCEB42022, 0xCA753D95,
	0xF23A8028, 0xF6FB9D9F, 0xFBB8BB46, 0xFF79A6F1, 0xE13EF6F4, 0xE5FFEB43, 0xE8BCCD9A, 0xEC7DD02D,
	0x34867077, 0x30476DC0, 0x3D044B19, 0x39C556AE, 0x278206AB, 0x23431B1C, 0x2E003DC5, 0x2AC12072,
	0x128E9DCF, 0x164F8078, 0x1B0CA6A1, 0x1FCDBB16, 0x018AEB13, 0x054BF6A4, 0x0808D07D, 0x0CC9CDCA,
	0x7897AB07, 0x7C56B6B0, 0x71159069, 0x75D48DDE, 0x6B93DDDB, 0x6F52C06C, 0x6211E6B5, 0x66D0FB02,
	0x5E9F46BF, 0x5A5E5B08, 0x571D7DD1, 0x53DC6066, 0x4D9B3063, 0x495A2DD4, 0x44190B0D, 0x40D816BA,
	0xACA5C697, 0xA864DB20, 0xA527FDF9, 0xA1E6E04E, 0xBFA1B04B, 0xBB60ADFC, 0xB6238B25, 0xB2E29692,
	0x8AAD2B2F, 0x8E6C3698, 0x832F1041, 0x87EE0DF6, 0x99A95DF3, 0x9D684044, 0x902B669D, 0x94EA7B2A,
	0xE0B41DE7, 0xE4750050, 0xE9362689, 0xEDF73B3E, 0xF3B06B3B, 0xF771768C, 0xFA325055, 0xFEF34DE2,
	0xC6BCF05F, 0xC27DEDE8, 0xCF3ECB31, 0xCBFFD686, 0xD5B88683, 0xD1799B34, 0xDC3ABDED, 0xD8FBA05A,
	0x690CE0EE, 0x6DCDFD59, 0x608EDB80, 0x644FC637, 0x7A089632, 0x7EC98B85, 0x738AAD5C, 0x774BB0EB,
	0x4F040D56, 0x4BC510E1, 0x46863638, 0x42472B8F, 0x5C007B8A, 0x58C1663D, 0x558240E4, 0x51435D53,
	0x251D3B9E, 0x21DC2629, 0x2C9F00F0, 0x285E1D47, 0x36194D42, 0x32D850F5, 0x3F9B762C, 0x3B5A6B9B,
	0x0315D626, 0x07D4CB91, 0x0A97ED48, 0x0E56F0FF, 0x1011A0FA, 0x14D0BD4D, 0x19939B94, 0x1D528623,
	0xF12F560E, 0xF5EE4BB9, 0xF8AD6D60, 0xFC6C70D7, 0xE22B20D2, 0xE6EA3D65, 0xEBA91BBC, 0xEF68060B,
	0xD727BBB6, 0xD3E6A601, 0xDEA580D8, 0xDA649D6F, 0xC423CD6A, 0xC0E2D0DD, 0xCDA1F604, 0xC960EBB3,
	0xBD3E8D7E, 0xB9FF90C9, 0xB4BCB610, 0xB07DABA7, 0xAE3AFBA2, 0xAAFBE615, 0xA7B8C0CC, 0xA379DD7B,
	0x9B3660C6, 0x9FF77D71, 0x92B45BA8, 0x9675461F, 0x8832161A, 0x8CF30BAD, 0x81B02D74, 0x857130C3,
	0x5D8A9099, 0x594B8D2E, 0x5408ABF7, 0x50C9B640, 0x4E8EE645, 0x4A4FFBF2, 0x470CDD2B, 0x43CDC09C,
	0x7B827D21, 0x7F436096, 0x7200464F, 0x76C15BF8, 0x68860BFD, 0x6C47164A, 0x61043093, 0x65C52D24,
	0x119B4BE9, 0x155A565E, 0x18197087, 0x1CD86D30, 0x029F3D35, 0x065E2082, 0x0B1D065B, 0x0FDC1BEC,
	0x3793A651, 0x3352BBE6, 0x3E119D3F, 0x3AD08088, 0x2497D08D, 0x2056CD3A, 0x2D15EBE3, 0x29D4F654,
	0xC5A92679, 0xC1683BCE, 0xCC2B1D17, 0xC8EA00A0, 0xD6AD50A5, 0xD26C4D12, 0xDF2F6BCB, 0xDBEE767C,
	0xE3A1CBC1, 0xE760D676, 0xEA23F0AF, 0xEEE2ED18, 0xF0A5BD1D, 0xF464A0AA, 0xF9278673, 0xFDE69BC4,
	0x89B8FD09, 0x8D79E0BE, 0x803AC667, 0x84FBDBD0, 0x9ABC8BD5, 0x9E7D9662, 0x933EB0BB, 0x97FFAD0C,
	0xAFB010B1, 0xAB710D06, 0xA6322BDF, 0xA2F33668, 0xBCB4666D, 0xB8757BDA, 0xB5365D03, 0xB1F740B4,
};

static unsigned int calculateCRC32 (const unsigned char *pStart, unsigned int uSize)
{
	unsigned int uCRCValue;
	unsigned char *pData;

	uCRCValue = 0xFFFFFFFF;
	pData = (unsigned char*)pStart;
	while (uSize --)
	{
		uCRCValue = CRC32_Table2[(uCRCValue ^ (*(pData++))) & 0xFF] ^ (uCRCValue >> 8);
	}
	return uCRCValue ^ 0xFFFFFFFF;
}

static unsigned int step_crc32(unsigned char ctl, const unsigned char pData) ;
static void step_crc_array(const unsigned char *pData, unsigned int len) {
	for(int i =0 ;i < len; i++) {
		step_crc32(1, pData[i]);
	}
}
void print_arry(unsigned char *data, unsigned int len ) {
    int i;
    for(i = 0; i < len ; i++) {
        printf("%02x ", data[i]);
		if(i%32 == 31  ) {
			printf("\n");
		}
    }
    printf("\n");
}

#define GET_AND_INIT_CRC() step_crc32(0,0)
#define CRC_ADD(data, len) step_crc_array(data,len)

/* mmap()目的：将硬件物理地址映射到用户虚拟地址空间，由2次数据拷贝变成1次数据拷贝！ */
int main(int argc, char** argv) 
{
#define FLAG (PROT_READ)
//#define FLAG (PROT_READ | PROT_WRITE)
    int fd, filelen;
    struct stat sb;
    char *mapped, *filename = mp3path;
	if(argc == 2) {
		filename = argv[1];
		
	}
    if ((fd = open (filename, O_RDWR)) < 0) {
        perror ("open");
    }
    /* 获取文件的属性 */
    if ((fstat (fd, &sb)) == -1) {
        perror ("fstat");
    }
    filelen = sb.st_size;
    /* 将文件映射至进程的地址空间 */
    if ((mapped = (char *) mmap (NULL, sb.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) == (void *) -1)
    {
        perror ("mmap");
    }
    close(fd);
    GET_AND_INIT_CRC();
	/*do something here*/
	int i;
	unsigned char *buf = (unsigned char *)mapped;
	unsigned int tlen = 0, wlen, dlen = sb.st_size;
	while(dlen > 0) {
		wlen = dlen;
		if(wlen > 1024) {
			wlen = 1024;
		}
		
		dlen-=wlen;
		buf = mapped+tlen;
		tlen+=wlen;
		printf("head %02x %02x %02x %02x , len %d/%d, crc is %x\n", buf[0], buf[1], buf[2], buf[3], wlen, tlen,  
		calculateCRC32(buf, wlen));
		print_arry(buf, wlen);
		CRC_ADD(buf,wlen);

	}
	
	
	printf("total crc is %x\n", GET_AND_INIT_CRC());
	
	munmap(mapped, sb.st_size); 
    return 0;
}


static unsigned int step_crc32(unsigned char ctl, const unsigned char pData) {
	enum{
		STEP_CRC_INIT = 0,
		STEP_CRC_ADD = 1,
	};
	static unsigned int uCRCValue = 0xFFFFFFFF;
	unsigned int ret = 0;
	switch(ctl) {
	case STEP_CRC_INIT:
		ret = uCRCValue ^ 0xFFFFFFFF;
		uCRCValue = 0xFFFFFFFF;
		break;
	case STEP_CRC_ADD:
		uCRCValue = CRC32_Table2[(uCRCValue ^ pData) & 0xFF] ^ (uCRCValue >> 8);
		ret = uCRCValue;
		break;
	}
	return ret;
} 





